OpAmp Question

Discussion in 'General Electronics Chat' started by joemmech, Feb 4, 2010.

  1. joemmech

    Thread Starter Member

    Jan 22, 2010
    32
    0
    Hi Guys, I have a question about OpAmps. What is the maximum voltage that can be supplied in the non-inverting and inverting input of an OpAmp? Is it ok if the supplied voltage in the inverting input and non-inverting input exceeds the Supply Voltage of the OpAmp? We are using the UA741 OpAmp and there is a note in the datasheet that says "The magnitude of the input voltage must never exceed the magnitude of the supply voltage or 15 V, whichever is less.", what does it mean? Do OpAmps have protection diodes/ ESD diodes inside?
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    Each op amp has different circuitry inside. If the datasheet says you have not to exceed the supply voltage then you have not.
     
  3. russ_hensel

    Well-Known Member

    Jan 11, 2009
    818
    47
    The spec sheet is right. On various op amps a variety of different bad ( unexpected ) things can happen. Reduce the input voltage, voltage divider or some sort of clipping circuit is the way to go.
     
  4. joemmech

    Thread Starter Member

    Jan 22, 2010
    32
    0
    How about protection diode, does the UA741 have a protection diode from Vcc+ and Vcc- going to the non-inverting and inverting input? We look at the specs in the datasheet but we cannot find any data that shows it has a protection diode.
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    No, that is something a designer might add. It is not very difficult to make a circuit in which an input never exceeds a particular level.
     
  6. joemmech

    Thread Starter Member

    Jan 22, 2010
    32
    0
    Thanks guys. It really helped a lot.
     
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